Art of cracking petroleum hydrocarbons.



J. W. COAST, .IR- ART OF CRACKING PETROLEUM HYDROCARBONS.

APPLICATION FILED MAY 5. I917. I, 1,250,801. Patented Dec. 18,1917.

i m l /a .sakkb .to obtain a. product known as 'gasolene,

UNITED STATES PATENT @FFIQE.

JOHN W. COAST, JR., 0F TULSA, OKLAHOMA, ASSIGNOR TO THE PROCESS COMPANY, A

CORPORATION .OF MARYLAND.

ART OF CRACKING PETROLEUM HYDROCARBONS.

Specification of Letters Patent.

Patented Dec. 18, 1917.

7 Application filed May 5, 1917. Serial No. 166,522.

To all whom it may concern:

Be it known that I, JOHN W. GoAs'r, Jr.,

a citizen of the United States of America,

which the following is a full, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to improvements in the art of cracking petroleum hydrocarbons gasolene substitute and cracked gasolene. One

' I of the objects is to improve the prior art by providing a method whereby high boiling point petroleum distillates or residues, or a mixture including such distillates or residues, may be cracked, vaporized and condensed very rapidly, with the result of ob taining a high grade low boiling point product.

The new method comprises a specific combination of steps or operations, performed in a particular sequence as will be hereinafter described. By subjecting the vapor to v materially reduce the this particular combination of operations, I

percentage of unsaturated hydrocarbons, obtain a lighter and better product andalmost entirely eliminate the objectionable color and odor, at the same time obtaining a large yield of the desired light fractions. To obtain these results, the vapor is preferably confined under a high pressure and conducted successively through a primary steam chamber, a reflux condenser, and then through a secondary steam chamber. In the preferred form of the invention, the vapor rising from' the liquid in the still enters the primary steam chamber, where it is acted upon by' a spray of relatively cool steam which condenses the heaviest fractions, returning them immediately to the still for redistillation. The

mixture of steam and vapor, passing fromthe primary steam chamber, flows through an air cooled reflux condenser where an intermediate fraction is condensed and returned to the still. Thereafter, the steam commingled with the remaining hydrocarbon vapor is conducted into the secondary steam chamber and subjected to the action turned to the still and a relatively small volume of the desired light fractions pass with the steam to the main condenser. The steam introduced near the still, commingles with and acts upon almost allof the vapor, and it remains with the vapor throughout the'several operations which take place-be tween the still and the discharge end of the main condenser. The fresh charge of steam introduced into the secondary steam chamber, acts upon the lightest fractions which escape to the main condenser. The efliciency of this steam is notimpaired by the heavier hydrocarbons, the latter being condensed before the vapor reaches the secondary steam chamber.

To obtain the several advantages previously pointed out, both steam chambers and the reflux condenser must be maintained under a high pressure, and it is desirable to condense the steam and light hydrocarbons under about atmospheric pressure. I, therefore, "preferably reduce the pressure'in the vapor line at a point beyond the steam chambers and reflux condenser.

The drawing is a diagrammatical view of an apparatus adapted for use in carrying out my method.

To illustrate the invention I have shown a retort, or still 1, arranged over a heatingchamber 2 and provided with a dome 3, which constitutes a primary steam chamber. Vapor passing from this steam chamber flows through an inclined vapor pipe 4:, an

. air cooled reflux-condenser 5, through a conlating valve 11, in the vapor pipe 9 may be regulated to maintain a predetermined pressure in the steam chambers and reflux con-' densers, also in the still 1. A steam pipe 12 is connected to a perforated discharge member 13 in the primary steam chamber-3. 14: designates a steam pipe connected to a discharge member '15 in the secondary steam chamber 8. A return pipe 16, leading from the air cooled condenser 5 to the still 1, allows reflux condensate to return to the still.

The" new method may be followed in cracking various heavy hydrocarbon products resulting from the treatment of crude petroleum, particularly such inexpensive hydrocarbons having boiling points higher than 350 F., the most beneficial results being obtained from hydrocarbons having boilingpoints ranging from 450 F to 700 F. The substances to be treated are introduced into the still in any suitable manner, and the valve 11 is adjusted to obtain the desired pressure in the still, reflux condensers and steam chambers. The pressure may range from 50 to 150 pounds 'per square inch, or even higher, but it is preferably maintained'at about'85 pounds per square inch. The, contents of the still are subjected to such a high degree of heat that the liquid will vaporize very rapidly. This temperature may. range from about 600 F. to 800 F., and is preferably maintained at about 725 F. The pressure in the apparatus is due to the expansive force of the vapors.

Owing to the intense heat and the rapid vaporization, a large volume of unconverted or partially converted hydrocarbons will flow from the still 1 to the primary steam chamber 8. At this point, the relatively cool steam, discharged from the perforated member 13, quickly condenses the heaviest fractions, returning them immediately for further treatment in the still. The heaviest fractions cannot escape from the steam chamber 3 to the vapor line, and until converted they are almost constantly subjected to the high degree of heat in the still. The steam passing into the primary steam chamber 3, is conducted entirely through the air cooled condensers 5 and 7, steam chamber 8, and into the main condenser 10. @n account of the high temperatures, the steam cannot condense until it reaches the main condenser. This steam flowing through the entire vapor line, including the reflux condensers, commingles freely with all of the vapor for a considerable period of time, thus performing its functions very eflectively.

The mixture of steam and hydrocarbon vapor flowing from the vapor pipe 4:, passes through the air cooled reflux condensers 5 and 7, where the intermediate high boiling point fractions are condensed and permitted to escape into the return pipe 16 leading to the still. All of the light hydrocarbon fractions escaping from the reflux condenser 77 to nascent the secondary steam chamber 8, are acted upon by the fresh charge of steam passing from the perforated discharge member .15 at a point beyond the air cooled condensers. This fresh charge of steam is cool enough to condense the heaviest fractions remaining in the vapor, and the condensate returns to the still by flowing through the air cooled condensers and return pipe 16. The fresh steam passing into the secondary steam chamber 8, removes the small residual amount of heavy fractions remaining in the light fractions which are to be condensed in the main condenser 10, and the efliciency of this steam is not impaired by the presence of a large volume of heavy hydrocarbons, its action being concentrated on removing the last. traces of heavy vapors from the lightest vapors immediately before the final condensing operation.

The hydrocarbon vapor is constantly undergoing the steam treatment at all points between the still and the main condenser 10. The mixture of steam and hydrocarbon vapor is confined under pressure between the still and the pressure regulating valve 11, and at the last mentioned point this mixture is permitted to expand and pass to the main condenser under a pressure of about one atmosphere.

By treating the hydrocarbon vapor in the manner herein shown and described, the capacity of the apparatus can be increased by vaporizing the liquid very rapidly, and the successive charges of steam .which enter and commingle with the compressed vapor at the still and beyond the reflux condensers, perform their functions most effectively. llf the preliminary charge of steam at the primary steam chamber 3 was omitted, the compressed vapor would not be subjected to the beneficial action of the steam while passing slowly through the vapor pipe 4 and reflux condensers 5 and 7. The secondary charge of fresh steam, introduced into the chamber 8 is also essential to this invention, for it acts upon the light fractions after they have been separated from the heavier fractions, and as previously pointed out, its action is not impaired by the presence of a large volume of carbons. Three things are essential to the combination involved in this invention. First, a suitable primary chamber where the steam is introduced into the vapor; second, an intermediate condenser through which the mixture of steam and hydrocarbon vapor is conducted, and third, a suitable supplemental oil-secondary steam chamber where steam is introduced into the mixture passing from the intermediate condenser. To obtain the desired results, the steam chambers the intermediate. condenser must be maintained under pressure.

The herein shown is in partially converted hydroan ap lication for patent filed by me May 5, 191 Serial Number 166,523. A method involving the use of steam is disclosed and more broadly claimed in an application filed by me Oct. 23, 1916, Serial Number 127,128.

I claim:

1. In the art of cracking petroleum hydrocarbons, the method which comprises heating and cracking such still, confining the resultant vapor under a pressure greater than two atmospheres, forcing relatively cool steam into the vapor while the latter is under pressure so as to condense the relatively heavy vaporized fractions, returning such condensate to the still, cooling the mixture of steam and hydrocarbon vapor so as to condense an intermediate fraction while the, mixture is confined under pressure, thereafter forcing relatively cool steam into the remaining mixture 'ofsteam and hydrocarbon vapor while the mixture is confined under pressure and hydrocarbons in a condensing the steam and hydrocarbon vapor.

2. In the art of cracking petroleum hydrocarbons, the method which comprises heating and cracking said hydrocarbons. in a still, confining the resultant vapor under a pressure greater than two atmospheres, introducing relatively cool steam into the vapor while the latter is confined under pres sure, conducting the mixture of steam and hydrocarbon vapor, under pressure, through a reflux condenser, introducing relatively cool steam under pressure into the remaining mixture of steam and hydrocarbon vapor, returning condensate from said steam and reflux condenser to the still, and condensing the mixture of steam and hydrocarbon vapor. y

In testimony that I claim the foregoing I hereunto affix my signature.

JOHN w. COAST, JR. 

